Contamination of liquid streams with various organic and inorganic pollutants is a serious global environmental problem affecting environment quality and represents significant threat to human health and safety. Substantial heavy metal contamination of aquatic environments arises from commercial mining and metal extraction processes, surfaces modification and protection processes, or communal and industrial waste sites resulting from a variety of active or defunct industrial fabrication and manufacturing activities. Similarly, significant organic water pollutants, like aliphatic, aromatic, or halogenated hydrocarbons and phenols are frequently associated with oil exploration, extraction and refining, chemicals production, or large-scale farming and food processing.
In addition to potential far significant environmental damage, polluted liquid streams represent dilute sources of desirable raw materials like heavy metals and metal oxides. For example, the Berkeley Mine Pit in Butte, Mont. alone represents an estimated 30 billion gallons of acid mine drainage which contains ˜180 ppm of copper along with other metals and thus could yield up to 22,000 tons of pure copper by use of a small treatment facility.
An economically relevant group of prior art methods of removal of heavy metal ions from liquid solutions is based on chemical precipitation. This process is generally burdened by complexity, high cost, clear preference for extremely large facilities and high-volume operations, and efficiency decrease with decrease in concentration of pollutants. One disadvantage concerns the resulting byproduct of precipitated sludge which becomes a concentrated yet mixed contaminant source of the toxins in the source material. The sludge mandates further processing and costly long term disposal as a highly toxic waste. Many similar disadvantages burden alternative heavy ion removal methods that may incorporate: filtration, ion exchange, foam generation and separation, reverse osmosis, or combinations of listed processes.
Considerable market research conducted by many strategic copper industry consultants indicated that high grade ore reserves are becoming exhausted. Producers increasingly may need a way to use their existing recovery equipment and processes to recover copper from their plentiful but presently unusable low-grade ore. Currently, they can't economically use the ore as resultant process streams containing the copper extracted from the ore are too weak and need strengthening (concentrating) to allow practical conventional copper production.
In contrast, the extraction technologies enabled by several aspects of the current invention may be adapted to alleviate at least some of the above considerations. Additional features of the current invention, for example, may contribute to the feasibility of modifying prior art electrowinning technology so that it can be used to economically concentrate copper generated in low-grade process streams instead of simply removing it. In general, the disclosed embodiments of the copper extraction technology may prepare a process stream so the customer can produce new copper from currently inaccessible sources with existing in-place processing infrastructure, equipment, and processes.
Some recent market research [e.g. Jan Mueller-Volmer, “Private Market Study Performed for the PI,” EnviroNet: Water and Environment Specialists: September 2009] estimate existence of 70 active copper mines using heap leach operations to generate ¼ of the world's copper production (9,000,000,000 lbs/yr). Moreover, heap leach use for copper production is growing as ore grades decline from resource depletion. Additionally, nearly ⅓ of the world's total copper reserves are locked in low-grade porphyry deposits considered be economically unsuitable for the prior art methods of extraction [e.g. in S. Wang, “Copper leaching from chalcopyrite concentrates,” J. Minerals, Metals, Materials Society, 55(7), p. 48. (2005); D. A. Singer, V. I. Berger, B. C. Moring, “Porphyry Copper Deposits of the World: Database and Grade and Tonnage Models,” U.S. Department of the Interior, Report 2008-1155 (2008).]
The present invention may provide some innovative features for unlocking this vast and vitally needed resource. Typical mines contain significant amounts of their copper in such unviable ores. This invention may allow the use of this “waste” ore and thereby increase average heap leach mine output by 25% and thus globally yield 3 Billion lbs/yr of newly recoverable copper.
Furthermore, additional features of embodiments of the current invention may allow for practical metal recovery from: Acid Rock Drainage (ARD), heavy metal and radionuclide contaminated sites, and metal contaminated industrial effluents such as electrowinning, plating plant, pickling operations, and circuit board manufacture (etching) discharges.